Expansion bit



Dec. 11, 1951 c w 2,577,986

EXPANSION BIT Filed June 18, 1946 2 SHEETS-SHEET l I N VENTOR ATTORNEYH. C. WILSON EXPANSION BIT Dec. 1l, l951 2 SHEETS-SHEET 2 Filed June 18,1946 ATTORNEY Patented Dec. 11, 1951 2,577,986 EXPANSION .311

Harry 0. Wilson Sherman Oaks, Califl, assignor 'to Robert H. Clark, LosAngeles, Calif.

Application June 18, 1946, Serial No. 677,486

8 Claims. (01. 145'127) This invention has to do with a bit and it .ismore particularly concerned with an adjustable bit of the type commonlyknown as an expansion bit. A general object of the present invention isto provide an improved, simplified and inexpensive construction forexpansion bits.

The present invention is concerned primarily with improvements in anexpansion bit such as is the subject of my copending applicationentitled Expansion Bit, Serial No. 566,838, new Patent No. 2,496,427,filed December 6, 1944.

It is an object of my present invention to provide a simplified andimproved clamp plate in an expansion bit of the character referred towhich plate serves to .hold the cutter to the body and is itself formedwith a cutting lip and a marginal spur which parts cooperate in cuttingthe central portion of the bore. An outstanding feature of the clampplate that I have provided is that it is a thin, light part thatminimizes the obstruction to the free flow of cuttings and which iseasily and inexpensively manufactured.

It is a further object of my present invention to provide an improved,highly efiicient cutter for an expansion bit. By my present invention Iprovide a cutter which is an elongate part clamped between the body andthe clamp plate to have a projecting portionthat cuts, which cutter isformed of sheet metaland has a bent or deflected outer end portion witha cutting blade disposed to cut at a most advantageous angle.

The various objects and features of my invention will be fullyunderstood from the following detailed description of a typicalpreferred form and application of my invention, throughout whichdescription reference is made to the accompanying drawings, in which:

Fig. 1 is a view showing the bit of the present invention in a typicalbrace by which it may be operated. Fig. 2 is an enlarged view of theworking or lower end portion of the bit, being an enlargement of apartof Fig. 1. Fig.3 is a plan section taken as indicated by line 3--3on Fig. 2. Fig. 4 is a perspective view of the clamp .plate of thepresent invention showing it disposed in .a substantially horizontalplane and showing it viewed from its upper side to illustrate the.manner in which it is shaped. Fig. '5 is a perspective view of thecutter that Lhaveprovided being a view showing the forward or leading:side of the cutter. Fig. 6 is a bottom plan view of the tool, being aview taken as indicated byline 6 -6 on Fig. 2. Fig. 7 is a sideelevation :of the bit taken as indicated by line 1-'! :on Fig. 3. Fig. 8is a side elevation of the bit .takenasindicated by line 8-8 'on Fig. 2.Fig. 9 is a vertical sectional view taken as indicated by line 9-9 onFig. 8 showing the construction at the center of the bit and Fig. 10 isa sectional view taken as indicated by line l0-l 0 on Fig. 9.

The bit'of the present invention is particularly useful for drillingholes in wood or the like-and in Fig. 1 of the drawings I have shown itin a typical brace such as is commonly employed for operating a bit ordrill, and inFig. 7 I have shown it in process of drilli g a holethrough a board B. 1

The bit involves, generally, a body ill, means II for mounting the bodyin a machine or operating tool, a'main cutter l2, means 13 for mountingthe cutter on the body so thatit projects downwardly and outwardlytherefrom, a leador feed screw l4 projecting from the lower end of thebody and a core cutter I5 on the lower end of the body.

The body in its preferred form is an elongate block of metal such assteel, having anouterside which is round or turned to be concentric withthe longitudinal axis of the bit. The upper end 2! of the body ispitched to extend upwardly and inwardly at an angle. The lower end 22 ofthe body is preferably a fiat part or surface disposed in a planepitched at a substantial angle relative to the axis .ofthe bit orrelative to a plane normal to the axisof the bit. In the caseillustrated the bottom 22 is pitched at an angle of about to a planenormal tothe axis of the bit. One side of the body is cut awayso thatthe body has a fiat side 23 extending parallelwith the axis of the bit.The cut in the side of the body is'made deep so that there is .asubstantial opening or clearance at the side of the body-at or adjacentthe face 23 to accommodate chips or cuttings.

The body has a central longitudinal opening formed through it. The upperend portion .24 of the opening is somewhat larger than the lower endportion so that the opening receives or accommodates parts of differentdiameters as will be hereinafterdescribed.

The means Ll provided for mounting-thebody A 3 stem with a finishedlower end portion 28 which fits tightly into the upper end portion 24 ofthe body opening. The stem in this case has an extension 29 of reduceddiameter fitting the small or reduced lower portion 25 of the bodyopening. The extension 29 projects below the lower end of the body toform the lead screw l4. Where the stem and body are formed separately asjust described they may be secured together in any suitable manner. Forinstance, it is practical and economical to sweat them together withsilver solder so that they, in effect, form a solid unit.

The cutter i2 is an elongate blade-carrying part carried by the body Into project downwardly and outwardly therefrom. The mounting means I3serves to hold the cutter in position so that it is rigidly or firmlyheld in the desired position of adjustment relative to the body. Inaccordance with my present invention the cutter I2 is formed of a plateor sheet of metal and it has a shank portion 30 shaped or formed to beV-shaped or channel-shaped incross sectional configuration and it has anouter active or tip portion 3| that projects from the body and which isdressed to have a forwardly facing cutting edge 32 and which is providedat its outermost end with a downwardly projecting lip or spur 33.

A cutter carrying channel 35 is provided in the bottom face 22 of thebody l0 and the means I3 clamps the shank of the cutter in the channel35. With my improved construction the shank 30 being V-shaped in crosssectional configuration has spaced or diverging flange-like side parts Xand Y. The channel 35 in the body I0 is formed so that it is V-shapedand receives the shank of the cutter so that the side Y thereof bearsagainst one side of the channel while the side X is substantiallyparallel with the bottom 22 of the body and so that the outer edges 36of the side X and Y respectively are in bearing engagement with theother side of the channel.

The cutter is arranged in the channel in the manner above described sothat the edge 36 of side X of the cutter faces in the direction that thecutter operates or is such as to advance and form a leading edge as thecutter is operated. The tip portion of the cutter is a highly importantfeature of the present invention since it is bent or turned back at apoint outward of the body In in a direction opposite to that in whichthe cutter moves into the work so that the side Y which continues fromthe shank portion to and along the tip portion, instead of extendingstraight out from the body, extends out and then rearwardly relative tothe direction of rotation of the body. The projecting portion of theside X is dressed to present the sharp or keen cutting edge 32, it beingpreferred to form this edge by grinding or otherwise dressing the sidepart X of the cutter at both its upper end lower sides. The side Y ofthe cutter continues from the shank portion to the tip portion where itgradually dies out or'diminishes in vertical extent until it terminatesat the outermost end of the cutter. As the strip of material out ofwhich the cutter is formed is shaped or bent to gain the tipconstruction just referred to the side X of the cutter widens somewhatas it approaches the extreme outer end of the cutter, thus presentingample stock behind the cutting edge so that the cutter can be repeatedlysharpened. The extreme outer end of the cutter, that is, the tip portionthereof, is merely bent down so that the spur 33 depends from the outerend of the 4 side X of the cutter. It is to be understood that the spurcan be pitched to give it proper clearance and that it can be sharpenedor dressed so that it presents a. sharp leading or cutting edge 33.

It is to be observed from the drawings and it will be apparent fromFigs. 3 and S of the drawings, how the cutting edge 32 presented by thecutter is at the forward leading portion of the side X as the cutter isrotated to advance into the work and it will be noted that the edge 32instead of being a simple straight cutting edge has a straight portion aprojecting substantially radially from the body while the main cuttingportion 1) of the edge is joined to the part a by a suitably curved partand then projects outwardly and rearwardly relative to the direction ofrotation of the tool. The extent of the edge portion a will varydepending upon the setting of the tool and unless the cutter is set toextend or project a substantial distance from the body the blade portiona will be entirely within the channel within the body so that thepitched portion 11 of the blade is the only part that is active or whichprojects to cut. By pitching the main cutting portion b of the cuttingedge outwardly and rearwardly the cutter has a desirable efficientshearing action that will cut wood by making acurl or shaving ratherthan acting to bite into the wood to tear or remove it in chunks.

In practice it is desirable to provide the cutter with means by whichthe user may determine the extent to which it is projecting from thebody. This may be done by providing a scale on one side or face of thecutter, preferably the side Y, to cooperate with the end edge 8| thatoccurs where the channel 35 intersects the curved exterior 20 of thebody, which edge may be straightened for the purpose of propercooperation with the scale.

The means l3 for mounting the cutter involves the channel 35 provided inthe bottom 22 of the body, as described, a clamp plate 44 arranged atthe lower end of the body to engage the outer or under side of thecutter side X as clearly shown in Figs. 2, 7, 8, 9 and 10 of thedrawings, and a screw 10 retaining the plate. The channel abovedescribed is preferably formed immediately adjacent the extension of thestem 23 in which case it is slightly offset from the center of the tooland it extends in the direction that the bottom 22 is pitched downwardlyrelative to the axis of the tool so that it carries the cutter with thetop portion thereof outward of and below the lower end of the bodyopposite the lowermost portion of the body. Further, it will be apparentfrom the drawings that the channel is made deep enough to all butcompletely receive the shank of the cutter, with the result that aportion of the side X of the cutter shank projects slightly beyond orbelow the bottom 22 of the body to be engaged by the plate 44. The clampplate 44 is, in accordance with my present invention, a fiat plate orbody of sheet metal that can be stamped punched, or otherwise formedinto the desired shape and in its preferred form it has, an outer curvedsurface 45 concentric with the axis of the bit and of the same size andcurvature as the outer size 20 of the body ID. The top side or face 46of the clamp plate opposes the end 22 of the body to be paralleltherewith or substantially parallel therewith while the lower side orbottom 41 is parallel with the top side 46. The plate 44 has a centralround opening 48 that passes the extension 29 of the stem 26; the roundopening being located to'pass the extension ofthe stem which isconcentric with the central axis of the bit and with the outer curvedsurface d5 of the plate.

In accordance with my invention I provide the plate M with a cutting lip50 and a depending spur 5| which forms the core cutter l5. To form orestablish the lip 55.! a cut is made in the clamp plate from its outercurved surface to the central opening ts and the portion of th plate atone side or defining one side of the cut is deflected or bent down sothat it forms the lip which is defiected somewhat downward from thelower side or bottom 4? of the plate. The lip 58 faces in the directionthat the tool turns or in the same direction as the cutting edge 32 andit is dressed away at 52 to establish a forward cutting edge 55. The outjust referred to is made in the plate 4.6 so that it occurs at the fiat.side 23 of the body H! with the result that the lip 50 projects from theflat side of the body as will be seen in Figs. 3 and 8 of the drawings,so that there is clearance or space above the lip to accommodatecuttings or chips made by the edge 55. At the other side of the cut,that is, forward of the lip 50, the plate is cut away as by dressingaway the plate so that it has a flat edge 60 coinciding with the fiatside 23 of the body, which fiat sided portion has its lower sidebevelled away at El to further provide chip clearance.

The spur of the core cutting means I 5, that is, the spur 5| on theplate 4-! is formed or established by making a transverse fiat cut 65 atthe lowermost portion of the plate, which cut is made to come close tothe very edge of the lowermost part of the plate but is spaced from itenough to leave the depending spur as shown in Figs. 2, 7 and 9 of thedrawings. By forming the spur at the lowermost portion of the plate andby doing so by means of a simple machine cut across the bottom of theplate, I am able to form an effective spur or core cutting projection asa part of or integral with the simple sheet metal plate withoutresorting to expensive forming or drawings operations such as areordinarily required in the formation of such a part. It is to i beobserved that the spur 5|, being located at the lowermost point of theplate 44, occurs at the lowermost part of the body I from which the maincutter projects so that the spur occurs adjacent the cutting edge 32 andit is to be observed that the spur is located about 90 around theperiphery of the plate 44 from the cutting edge 55 of the lip. Bylocating the spur ad- J'acent the edge 32 of the main cutter to cutslightly forward thereof, as shown throughout the drawings, the spurserves to make a out between the surfaces cut by the edges 55 and 32With the result that the cutter as a whole cuts through a body of woodor the like making two distinct chips or curls as it operates.

The means It includes, in addition to the plate 44, a screw 70 whichextends through the body downwardly at an angle from the upper endportion thereof to project from the bottom face 22 and thread into anopening H provided in the plate. A bore '52 is provided in the body toextend from the beveled upper end thereof diagonally downward in adirection normal to the bottom end face 22 and intersecting the centralaxis of the bit, and thus passing through the tool the bore 12 passesthrough the body and also through a portion of the stem and itsextension, as will be seen in Fig. 9. The screw has a head 14 at theupper end of the body and its lower end is provided with a thread toengage in the threaded opening II .in'the plate 44. It will be apparentthat as th screwis tightened the plate is drawn toward the face .22 ofthe body so that it clamps or -,bears .against the side X of the cutterclamping th cutter tightly in the channel in the body. The'feed screw I4is formed by continuing the projection 29 beyond the lower end of thebody and thevprojecting portion of the extension is tapered and threadedwhile the extreme tip end is flattened or made somewhat diamond shapedas shown in the drawings.

From the foregoing description and from the drawings it will beobservedthat I have provided a cutter that projects from the body I ii and whichhas a simply formed yet highly effective cutting edge arranged at a mostadvantageous angle. The cutter is formed of sheet metal and is carriedin thechannel of the body so that'the side X of the cutterliessubstantially in theplane of cut of the edge 32, and it is readilydressed back from the edge to present a thin sharp cutting part thatwill out wood in a most eflicient manner and far better than will acutter that is blunt and does not present a sharp chisel-like edge. Itis also to be observed that by forming the cutter of sheet metal it canbe readily turned back so that its tip portion extends ata mostadvantageous angle and likewise it can be readily bent down at itsextreme outer end to form the spur 33.

.It will also be apparent from the present disclosure that the plate 44that I have provided not only serves as a simple, effective means ofholding the cutter in engagement with the body but it is also easilyformed from a plate or body of sheet metal andcan be readily worked orshaped to present the lip and the spur 5|. In manufacture the plate thatI have provided can be made easily and quickly and in operation it cutsin a most satisfactory manner, serving to cut a core or central openingfrom the extension of the shank outward to the point where the maincutter starts to cut. The extent to which the main cutter cuts or, thatis, the size of the hole made by the bit, will be deiermined by. theadjustment of the main cutter or, in other words, by the amount of themain cutter that projects outward beyond the wall 29 of the body.

Having described only a typical preferred form and application of myinvention, I do not wish to be limited or resLricted to the specificdetails herein set forth, but wish to reserve to myself any variation ormodifications that may appear to those skilled in the art and fallwithin the scope of the following claims:

Having described my invention, I claim:

1. A bit of the character described including, a central body with alower end face in a plane inclined to a plane normal to the axis of thebit, there being a downwardly opening channel in the lower end face ofthe body, a cutter carried in the channel to project from one side ofthe body and to a point below the lower end of thebody, a plate opposingsaid lower end face and retainin the cutter in the channel, and meanssecuring the plate to the body, the cutter being V-shaped in crosssection and having its projecting portion turned back from the directionof cut.

2. A bit of the character described including, a stem, a fixed rigidcentral body on the lower end of the stem and having a, channel in itslower end, a cutter carried in the channel to project from one side ofthe body and to a point below the lower end of the body, a plateretaining the cutter in the channel, means securing the plate to thebody, the cutter being V-shaped in cross section and having itsprojecting portion turned back from the direction of cut, the leadinglongitudinal edge of the cutter being sharpened to cut, the plate beinga sheet metal disc notched from the edge and pro jecting down adjacentthe notch to form a forwardly facing lip with a sharpened forward edge.

3. A bit of the character described including, a central stem, a centralbody permanently fixed on the lower end of the stem to be rigidtherewith and having a channel in its lower end, a cutter carried in thechannel to project from one side of the body and to a point below thelower end of the body, a plate separate from the body and stem andopposing the lower end of the body to retain the cutter in the channel,means securing the plate to the body, the plate being a sheet metal discnotched from the edge and depending down adjacent the notch to form adepending forwardly facing lip with a sharpened forward edge.

4. A cutter for an expansion bit including a continuous strip of sheetmetal having a shank portion uniformly V-shaped in cross sectionthroughout its length, there being a tip portion projecting from theshank portion and widening as it projects from the shank portion, theleading edge of the tip portion being sharpened.

5. A cutter for an expansion bit including, a strip of sheet metalhaving a straight elongate shank portion V-shaped in cross sectionthroughout its length to have substantially equal side portions with theouter edge of one side portion sharpened, the strip having a tip portionextending from the shank portion at anangle thereto with a sharpenededge continuous with the sharpened end of the shank portion.

6. A cutter for an expansion bit including, a strip of sheet metalhaving a straight elongate shank portion V-shaped in cross sectionthroughout its length to have substantially equal side portions with theouter edge of one side portion sharpened, the strip having a tip portionextending from the shank portion at an angle thereto with a sharpenededge continuous with the sharpened end of the shank portion and formingan obtuse angle therewith, the tip portion fiattening and becoming widerthan the shank portion as it projects therefrom,

7. A cutter holding clamp for an expansion bit including a substantiallyround sheet metal plate with a central screw passing opening and aneccentric retainer receiving opening and having a notch-like openingextending into it from its peripheral edge, the notch-like openinghaving side edges that extend in from the periphery of the plate, theplate having a portion adjacent one of the edges of the notch-likeopening projecting below the bottom side of the plate and beingsharpened forming a cutting lip.

8. A cutter holding'clamp for an expansion bit including a substantiallyround sheet metal plate with a central screw passing opening and alsohaving a threaded retainer receiving opening eccentric to the centralopening. there being a notch in the plate from the edge andcommunicating with the central opening, one side edge of the notch beingoffset downwardly from the plane of the plate and sharpened forming acutting lip.

HARRY C. WILSON.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 567,977 Hagerty Sept. 22, 1896843,832 Lingol Feb. 12, 1907 916,527 Beugler Mar. 3 1909 1,056,670Hayden Mar. 18, 1913 1,283,414 Kitchen Oct. 29, 1918 1,576,676 RubleMar. 16, 1926 1,585,000 Thomson May 18, 1926 FOREIGN PATENTS NumberCountry Date 533,808 Germany Sept. 18, 1931

